This invention relates to a system for reporting back to a centrally located office, the viewing of certain premium programming for which a subscriber is billed in addition to his regular monthly subscription fee. This practice is popularly referred to as "pay-per-view" (PPV). More specifically, the subject invention relates to the most desirable type of PPV, known as "impulse pay-per-view" (IPPV). An IPPV system allows a subscriber to order a program at the last minute.
Early PPV systems worked with one way addressable set-top terminals. A subscriber who wished to order a PPV event did so by calling an operator and orally placing his order. The operator entered the order into a computer, which then transmitted authorization to the subscriber's set-top terminal.
This system suffers from the requirement of using the telephone and a human operator. This raises the cost of handling PPV requests, and effectively eliminates IPPV as a viable service since only a limited number of people could call in during the last minutes before a program begins. Therefore, the majority of people desiring to view a program must order it long before it begins.
Some prior art exists which purports to solve the IPPV problem. One such system employs a two-way cable television (CATV) plant, in which the set-top terminal may be equipped for transmitting a signal back to the headend ("upstream transmission") on a suitable (frequency, such as between 5 MHz and 30 MHz. The terminal transmits information as to what programs are being or have been viewed to a computer at the headend. This system suffers from the fact that no protocols have been developed which operate efficiently in an environment of an exceedingly large number of talkers who speak very little, but who must be serviced quickly when they do speak. Further, two-way CATV plants have proved difficult to maintain with adequate integrity to permit reliable return transmission, and the cost of the plant is excessive compared to the revenues to be gained from IPPV.
Another system uses credits downloaded to the terminal, and then makes deductions against the credits when a program is viewed. At the end of the month, certain alpha-numeric characters are displayed, indicating programs viewed. The subscriber writes these characters on a card which is mailed to the CATV operator. This system suffers from excessive delay in reporting programs watched, a limited number of programs which can be viewed (due to the limited number of characters a subscriber can be expected to write down), and the possibility of unrecoverable errors in transcription.
A similar system is disclosed in U.S. Pat. No. 4,484,217 to Block et al. In this system, credits are downloaded to the terminal and deductions are made when programs are viewed. An indicator informs the subscriber that the stored credit has expired or is low. The headend office, upon receipt of payment, will add credits to the subscriber's terminal and the indicator will be extinguished. In this system the subscriber must pay in advance and may miss programs due to the delay in crediting his account.
U.S. Pat. No. 3,676,580 to Beck discloses a system in which telephone lines are used to transmit billing information back to the central office. In Beck's system each subscriber is provided with a transponder which will transmit the billing information along the telephone lines. Since each subscriber's information is reported over a separate telephone line, the cost is excessive as is the time required to obtain viewing information on thousands of customers.
European Patent Application No. 0128481 discloses the use of remote units at a plurality of locations for accumulating and transmitting information about a plurality of viewers to the central office. At pre-selected times, the remote unit initiates a telephone call to the central office and transmits its stored data. This system has a cable converter associated with each user that will receive instructions from the user and supply a television signal accordingly. Each converter is also connected to one of the remote units and the information regarding the selected programs is supplied to the remote unit for storage and eventual transmission to the headend. Since the remote unit is directly connected to the cable converter, the unit must be relatively close to the subscriber. This necessitates a large number of remote units throughout the cable system and, consequently, a large number of telephone links to transmit the stored information back to the headend.